Question

Need to choose optimal data structure for fast work with list of locations and regions.

There is simple POJO for locations(cities):

public class Location {

    private String name;
    private int post; //id

And for regions(districts):

public class Region {
    private String name;
    private int id;
    private List<Location> cities;

And finally I have List of Region objects.
What I need to do:

1. Search Locations name by its post(id)
2. Search Locations post by its name. Note: Name is not unique, so I need to prefer some concrete Location over another in case of identical names

The question is what data structure should I use?
I am thinking of TreeMap with contains ALL the Locations from ALL regions. So I can fast get location by Name(string).
For p 1. I have solution: post of Location contains id of Region. So If Region have id=1, then its Locations post will be 10001, 10002 etc.
Or maybe I need to choose some new Collections type introduced by Guava, since it already present in project?

Answer 1

Add all locations to two HashMaps:

1. one with the all Locations with Location name as the key and a List of Location as value.
2. other with id as the key and the Location as the value?

Preferably hide the two hashmaps in one class doing the lookups for you.

Or am I missing something?